Elie Metchnikoff, Sub-Director of the Pasteur Institute in Paris,
was born May 15, 1845, in the province of Kharkov, Russia, and has
worked at the Pasteur Institute since 1888. The greater part of
Metchnikoff's work is concerned with the most intimate processes of
the body, and notably the means by which it defends itself from the
living agents of disease. He is, indeed, the author of a standard
treatise entitled "Immunity in Infective Diseases." His early work
in zoology led him to study the water-flea, and thence to discover
that the white cells of the human blood oppose, consume, and
destroy invading microbes. Latterly, Metchnikoff has devoted
himself in some measure to more general and especially
philosophical studies, the outcome of which is best represented by
the notable volume on "The Nature of Man," which was published at
Paris in 1903.
_I.--Disharmonies in Nature_
Notwithstanding the real advance made by science, it cannot be disputed
that a general uneasiness disturbs the whole world to-day, and the
frequency of suicide is increased greatly among civilised peoples. Yet
if science turns to study human nature, there may be grounds for hope.
The Greeks held human nature and the human body in high esteem, and
among the Romans such a philosopher as Seneca said, "Take nature as your
guide, for so reason bids you and advises you; to live happily is to
live naturally." In our own day Herbert Spencer has expressed again the
Greek ideal, seeking the foundation of morality in human nature itself.
But it has often been taught that human nature is composed of two
hostile elements, a body and a soul. The soul alone was to be honoured,
while the body was regarded as the vile source of evils. This doctrine
has had many disastrous consequences, and it is not surprising that in
consequence of it celibacy should have been regarded as the ideal state.
Art fell from the Greek ideal until the Renaissance, with its return to
that ideal, brought new vigour. When the ancient spirit was born again
its influence reached science and even religion, and the Reformation was
a defence of human nature. The Lutheran doctrines resumed the principle
of a "development as complete as possible of all the natural powers" of
man, and compulsory celibacy was abolished.
The historical diversity of opinion regarding human nature is what has
led me to the attempt to give an exposition of human nature in its
strength and in its weakness. But, before dealing with the man himself,
we must survey the lower forms of life.
The facts of the organised world, before the appearnace of man, teach us
that though we find change and development, development does not always
take a progressive march. We are bound to believe, for instance, that
the latest products of evolution are not human beings, but certain
parasites which live only upon, or in, the human body. The law in nature
is not of constant progress, but of constant tendency towards
adaptation. Exquisite adaptations, or harmonies, in nature are
constantly met with in the world of living beings. But, on the other
hand, any close investigation of organisation and life reveals that
beside many most perfect harmonies, there are facts which prove the
existence of incomplete harmony, or even absolute disharmony.
Rudimentary and useless organs are widely distributed. Many insects are
exquisitely adapted for sucking the nectar of flowers; many others would
wish to do the same, but their want of adaptation baffles them.
It is plain that an instinct, or any other form of disharmony, leading
to destruction, cannot increase or even endure very long. The perversion
of the maternal instinct, tending to abandonment of the young, is
destructive to the stock. In consequence, individuals affected by it do
not have the opportunity of transmitting the perversion. If all rabbits,
or a majority of them, left their young to die through neglect, it is
evident that the species would soon die out. On the contrary, mothers
guided by their instinct to nourish and foster their offspring will
produce a vigorous generation capable of transmitting the healthy
maternal instinct so essential for the preservation of the species. For
such a reason harmonious characters are more abundant in nature than
injurious peculiarities. The latter, because they are injurious to the
individual and to the species, cannot perpetuate themselves
indefinitely.
In this way there comes about a constant selection of characters. The
useful qualities are handed down and preserved, while noxious characters
perish and so disappear. Although disharmonies tend to the destruction
of a species, they may themselves disappear without having destroyed the
race in which they occur.
This continuous process of natural selection, which offers so good an
explanation of the transmutation and origin of species by means of
preservation of useful and destruction of harmful characters, was
discovered by Darwin and Wallace, and was established by the splendid
researches of the former of these.
Long before the appearance of man on the face of the earth, there were
some happy beings well adapted to their environment, and some unhappy
creatures that followed disharmonious instincts so as to imperil or to
destroy their lives. Were such creatures capable of reflection and
communication, plainly the fortunate among them, such as orchids and
certain wasps, would be on the side of the optimists; they would declare
this the best of all possible worlds, and insist that to secure
happiness it is necessary only to follow natural instincts. On the other
hand, the disharmonious creatures, those ill adapted to the conditions
of life, would be pessimistic philosophers. Consider the case of the
ladybird, driven by hunger and with a preference for honey, which
searches for it on flowers and meets only with failure, or of insects
driven by their instincts into the flames, only to lose their wings and
their lives; such creatures, plainly, would express as their idea of the
world that it was fashioned abominably, and that existence was a
mistake.
_II.--Disharmonies in Man_
As for man, the creature most interesting to us, in what category does
he fall? Is he a being whose nature is in harmony with the conditions in
which he has to live, or is he out of harmony with his environment? A
critical examination is needed to answer these questions, and to such an
examination the pages to follow are devoted.
Science has proved that man is closely akin to the higher monkeys or
anthropoid apes--a fact which we must reckon with if we are to
understand human nature. The details of anatomy which show the kinship
between man and the apes are numerous and astonishing. All the facts
brought to light during the last forty years have supported this truth,
and no single fact has been brought against it. Quite lately it has been
shown that there are remarkable characters in the blood, such that,
though by certain tests the fluid part of human blood can be readily
distinguished from that of any other creature, the anthropoid apes, and
they alone, furnish an exception to this rule. There is thus verily a
close blood-relationship between the human species and the anthropoid
apes.
But how man arose we do not know. It is probable that he owes his origin
to a mutation--a sudden change comparable with that which De Vries
observed in the case of the evening primrose. The new creature possessed
a brain of abnormal size placed in a spacious cranium which allowed a
rapid development of intellectual faculties. This peculiarity would be
transmitted to the descendants, and as it was a very considerable
advantage in the struggle for existence, the new race would hold its
own, propagate, and prevail.
Although he is a recent arrival on the earth, man has already made great
progress, as compared with his ancestors the anthropoid apes, and we
learn the same if we compare the higher and lower races of mankind. Yet
there remain many disharmonies in the organisation of man, as, for
instance, in his digestive system. A simple instance of this kind is
furnished by the wisdom teeth. The complete absence of all four wisdom
teeth has no influence on mastication, and their presence is very
frequently the source of illness and danger. In man they are indeed
rudimentary organs, providing another proof of our simian origin. The
vermiform appendix, so frequently the cause of illness and death, is
another rudimentary organ in the human body, together with the part of
the digestive canal to which it is attached. The organ is a very old
part of the constitution of mammals, and it is because it has been
preserved long after its function has disappeared that we find it
occurring in the body of man.
I believe that not only the appendix, but a very large part of the
alimentary canal is superfluous, and worse than superfluous. It is, of
course, of great importance to the horse, the rabbit, and some other
mammals that live exclusively on grain and herbage. The latter part of
the alimentary canal, however, must be regarded as one of the organs
possessed by man and yet harmful to his health and life. It is the cause
of a series of misfortunes. The human stomach also is of little value,
and can easily be dispensed with, as surgery has proved. It is because
we inherit our alimentary canal from creatures of different dietetic
habits that it is impossible for us to take our nutriment in the most
perfect form. If we were only to eat substances that could be almost
completely absorbed, serious complications would be produced. A
satisfactory system of diet has to make allowance for this, and in
consequence of the structure of the alimentary canal has to include in
the food bulky and indigestible materials, such as vegetables. Lastly,
it may be noted that the instinct of appetite in man is largely
aberrant. The widespread results of alcoholism show plainly the
prevalent existence in man of a want of harmony between the instinct for
choosing food and the instinct of preservation.
Far stronger than the social instinct, and far older, is the love of
life and the instinct of self-preservation. Devices for the protection
of life were developed long before the evolution of mankind, and it is
quite certain that animals, even those highest in the scale of life, are
unconscious of the inevitability of death and the ultimate fate of all
living things. This knowledge is a human acquisition. It has long been
recognised that the old attach a higher value to life than do the young.
The instinctive love of life and fear of death are of importance in the
study of human nature, impossible to over-estimate.
The instinctive love of life is preserved in the aged in its strongest
form. I have carefully studied the aged to make certain on this point.
It is a terrible disharmony that the instinctive love of life should
manifest itself so strongly when death is felt to be so near at hand.
Hence the religions of all times have been concerned with the problem of
death.
_III.--Science the Only Remedy for Human Disharmonies_
In religion and in philosophy throughout their whole history we find
attempts to combat the ills arising from the disharmonies of the human
constitution.
Ancient and modern philosophies, like ancient and modern religions, have
concerned themselves with the attempt to remedy the ills of human
existence, and instinctive fear of death has always ensured that great
attention has been paid to the doctrine of immortality.
Science, the youngest daughter of knowledge, has begun to investigate
the great problems affecting humanity. Her first steps, taken along the
lines first clearly laid down by Bacon, were slow and halting. But
medical science has lately made great progress, and has gone very far to
control disease, especially in consequence of the work of Pasteur. It is
said that science has failed because, for instance, tuberculosis
persists, but tuberculosis is propagated not because of the failure of
science, but because of the ignorance and stupidity of the population.
To diminish the spread of tuberculosis, of typhoid fever, of dysentery,
and of many other diseases, it is necessary only to follow the rules of
scientific hygiene without waiting for specific remedies.
Science offers us much hope also when it is directed to the study of old
age and the phenomena which lead to death.
Man, who is the descendant of some anthropoid ape, has inherited a
constitution adapted to an environment very different from that which
now surrounds him. He is possessed of a brain very much more highly
developed than that of his ancestors, and has entered on a new path in
the evolution of the higher organisms. The sudden change in his natural
conditions has brought about a large series of organic disharmonies,
which become more and more acutely felt as he becomes more intelligent
and more sensitive; and thus there has arisen a number of sorrows which
poor humanity has tried to relieve by all the means in its power.
Humanity in its misery has put question after question to science, and
has lost patience at the slowness of the advance of knowledge. It has
declared that the answers already found by science are futile and of
little interest. But science, confident of its methods, has quietly
continued to work. Little by little the answers to some of the
questions that have been set have begun to appear.
Man, because of the fundamental disharmonies in his constitution, does
not develop normally. The earlier phases of his development are passed
through with little trouble; but after maturity greater or lesser
abnormality begins, and ends in old age and death that are premature and
pathological. Is not the goal of existence the accomplishment of a
complete and physiological cycle in which occurs a normal old age,
ending in the loss of the instinct of life and the appearance of the
instinct of death? But before attaining the normal end, coming after the
appearance of the instinct of death, a normal life must be lived; a life
filled all through with the feeling that comes from the accomplishment
of function. Science has been able to tell us that man, the descendant
of animals, has good and evil qualities in his nature, and that his life
is made unhappy by the evil qualities.
But the constitution of man is not immutable, and perhaps it may be
changed for the better. Morality should be based not on human nature in
its existing condition, but on ideal human nature, as it may be in the
future. Before all things, it is necessary to try to amend the evolution
of human life, that is to say, to transform its disharmonies into
harmonies. This task can be undertaken only by science, and to science
the opportunity of accomplishing it must be given. Before it is possible
to reach the goal mankind must be persuaded that science is all-powerful
and that the deeply-rooted existing superstitions are pernicious. It
will be necessary to reform many customs and many institutions that now
seem to rest on enduring foundations. The abandonment of much that is
habitual, and a revolution in the mode of education, will require long
and painful effort. But the conviction that science alone is able to
redress the disharmonies of the human constitution will lead directly to
the improvement of education and to the solidarity of mankind.